chore(deps): update dependency @types/node to v18 (#969)

[![Mend Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [@types/node](https://togithub.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/node) ([source](https://togithub.com/DefinitelyTyped/DefinitelyTyped)) | [`^16.0.0` -> `^18.0.0`](https://renovatebot.com/diffs/npm/@types%2fnode/16.18.3/18.11.9) | [![age](https://badges.renovateapi.com/packages/npm/@types%2fnode/18.11.9/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/npm/@types%2fnode/18.11.9/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/npm/@types%2fnode/18.11.9/compatibility-slim/16.18.3)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/npm/@types%2fnode/18.11.9/confidence-slim/16.18.3)](https://docs.renovatebot.com/merge-confidence/) |

---

### Configuration

📅 **Schedule**: Branch creation - "after 9am and before 3pm" (UTC), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Mend Renovate](https://www.mend.io/free-developer-tools/renovate/). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/nodejs-speech).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzMi4yNDEuMTEiLCJ1cGRhdGVkSW5WZXIiOiIzNC4xMS4xIn0=-->

Author: renovate-bot

packages/google-cloud-node/package.json

@@ -55,7 +55,7 @@
   },
   "devDependencies": {
     "@types/mocha": "^9.0.0",
-    "@types/node": "^16.0.0",
+    "@types/node": "^18.0.0",
     "@types/sinon": "^10.0.0",
     "c8": "^7.0.0",
     "codecov": "^3.0.2",